Facial disfigurement is treated like an infectious disease

The behavioral avoidance of people with facial disfigurement is well documented, but its psychological basis is poorly understood. Based upon a disease avoidance account of stigmatization, we conducted the first empirical test of whether facial disfigurement—naevus flammeus (a port wine stain) here—can trigger the same set of emotional and behavioral responses as a contagious disease (influenza). Ninety-eight participants contacted props, which they had seen used either by a healthy confederate or by a confederate simulating medical conditions affecting the face—birthmark and influenza. Behavioral avoidance (e.g., willingness to handle the prop) and facial display of disgust were recorded across five levels of prop contact varying from no contact to contact with the mouth. Behavioral avoidance and disgust displays, especially with oral contact, were equivalent in the birthmark and influenza conditions, with both significantly exceeding reactions to the healthy confederate. These results support the theory that humans have an evolved predisposition to avoid individuals with disease signs, which is mediated by the emotion of disgust. This implicit avoidance occurs even when they know explicitly that such signs—the birthmark here—result from a noncontagious condition.     

Frequency and recency of infection and their relationship with disgust and contamination sensitivity

Both disgust and contamination sensitivity likely evolved to protect us from infectious disease. Paradoxically, disgust may be reduced by frequent exposure to disgust-inducing cues — cues most likely to occur in disease-rich environments. In this study, we examined whether more frequent or recent illness might act to reverse this process. To test this, we surveyed 616 adults, obtaining illness frequency and recency data, disgust and contamination sensitivity, and a variety of control measures. Heightened contamination sensitivity was associated with more frequent infectious illness, but not with recency of infection. We also found that participants who had heightened contamination sensitivity and who were also more disgust sensitive had significantly fewer recent infections. These findings suggest that frequent illness may up-regulate contamination sensitivity potentially counteracting the effects of exposure on disgust. More importantly, these data provide the first direct evidence of a protective effect of contamination and disgust, against infectious disease.     

Contamination sensitivity and the development of disease-avoidant behaviour

Owing to their developing cognitive abilities and their limited knowledge about the biological basis of illness, children often have less expertise at disease avoidance than adults. However, affective reactions to contaminants through the acquisition of disgust and the social and cultural transmissions of knowledge about contamination and contagion provide impetus for children to learn effective disease-avoidant behaviours early in their development. In this article, we review the ontogenetic development of knowledge about contamination and contagion with particular attention to the role of socialization and culture. Together with their emerging cognitive abilities and affective reactions to contaminants, informal and formal cultural learning shape children's knowledge about disease. Through this process, the perceptual cues of contamination are linked to threats of disease outcomes and can act as determinants of disease-avoidant behaviours.     

Why disgust matters

The new synthesis about disgust is that it is a system that evolved to motivate infectious disease avoidance. There are vital practical and intellectual reasons why we need to understand disgust better. Practically, disgust can be harnessed to combat the behavioural causes of infectious and chronic disease such as diarrhoeal disease, pandemic flu and smoking. Disgust is also a source of much human suffering; it plays an underappreciated role in anxieties and phobias such as obsessive compulsive disorder, social phobia and post-traumatic stress syndromes; it is a hidden cost of many occupations such as caring for the sick and dealing with wastes, and self-directed disgust afflicts the lives of many, such as the obese and fistula patients. Disgust is used and abused in society, being both a force for social cohesion and a cause of prejudice and stigmatization of out-groups. This paper argues that a better understanding of disgust, using the new synthesis, offers practical lessons that can enhance human flourishing. Disgust also provides a model system for the study of emotion, one of the most important issues facing the brain and behavioural sciences today.     

Compensatory up-regulation of behavioral disease avoidance in immuno-compromised people with rheumatoid arthritis

Disgust and disease-related cues can activate the immune system. Here, we test whether immuno-suppression is associated with an up-regulation of cognitions and behaviors that assist in disease avoidance. People with rheumatoid arthritis (RA), who have a heightened risk of infection-related morbidity and mortality, were compared to age, gender and demographically matched healthy controls on a range of disease avoidance tasks. People with RA scored higher on reports of behavior likely to control infection, were more accurate in spotting individuals who were sick, and showed disease-specific ethnocentrism, ascribing a greater risk of contracting disease to non-Caucasians, although having no overall propensity for greater racism on the Modern Racism Scale. Contrary to predictions, disgust sensitivity (DS) did not differ between groups, however among people with RA, DS was found to be lower in those taking drugs that can increase infection risk. While more explicit disease avoidance behaviors are clearly up-regulated in people with RA, changes in DS may have a different and perhaps more biological casual basis.     

Is plasticity in mating preferences adapted to perceived exposure to pathogens?

Humans are unique among primates due to a lack of typical thermally insulating fur. The ectoparasite avoidance mediated by the mate choice hypothesis suggests that the loss of body hair reduces the risk of infection by ectoparasites and that the movement toward nudity may have been enforced by parasite-mediated sexual selection. In this study, we investigated two possible predictions of this hypothesis: (1) that preferences for hairless bodies increase with exposure to environmental pathogens and (2) that disgust sensitivity to the pathogens’ threat predicts the degree to which a woman will prefer hairless bodies. Using an experiment comparing the preferences of 88 women for shaved vs. hairy pictured versions of 20 male torsos, we found that exposure to the visual cues of pathogens does not predict preferences for a male chest nor does the individual disgust sensitivity to disease-related invertebrates. Overall, the results suggest that female perception of male trunk hair is not associated with a risk of contamination, which questions the salience of the ectoparasite avoidance hypothesis in explaining the loss of body hair in humans.     

Disgust as an adaptive system for disease avoidance behaviour

Disgust is an evolved psychological system for protecting organisms from infection through disease avoidant behaviour. This 'behavioural immune system', present in a diverse array of species, exhibits universal features that orchestrate hygienic behaviour in response to cues of risk of contact with pathogens. However, disgust is also a dynamic adaptive system. Individuals show variation in pathogen avoidance associated with psychological traits like having a neurotic personality, as well as a consequence of being in certain physiological states such as pregnancy or infancy. Three specialized learning mechanisms modify the disgust response: the Garcia effect, evaluative conditioning and the law of contagion. Hygiene behaviour is influenced at the group level through social learning heuristics such as 'copy the frequent'. Finally, group hygiene is extended symbolically to cultural rules about purity and pollution, which create social separations and are enforced as manners. Cooperative hygiene endeavours such as sanitation also reduce pathogen prevalence. Our model allows us to integrate perspectives from psychology, ecology and cultural evolution with those of epidemiology and anthropology. Understanding the nature of disease avoidance psychology at all levels of human organization can inform the design of programmes to improve public health.     

Health and the avoidance of macroparasites: a preliminary cross-cultural study

Some evolutionary explanations of cross-cultural differences propose that human personality is caused by pathogen stress. Both xenophobia and ethnocentrism evolved under conditions with high parasite prevalence. Further, inter-individual variation in disgust or fear of parasites is expected to be influenced by human health, where healthy people should express lower disgust sensitivity to parasites. We examined inter-individual variation of children’s fear, disgust and self-perceived danger between two distinct cultures differing in overall pathogen prevalence. We found that children were able to distinguish between disease-relevant and disease-irrelevant groups of invertebrates and that children in regions with high pathogen prevalence expressed greater fear, disgust and self-perceived danger of all animals, irrespective of disease threat. After controlling for confounding factors, better health of children was associated with lower perceived danger of disease-relevant animals. Gender differences were found only in conditions with low pathogen stress. Our results support the idea that cross-cultural differences in human perception of animals are mediated by pathogen threat. Further research is necessary to investigate causal relationship between human health and avoidance of potentially hazardous animals.     

Re-evaluating the relationship between pathogen avoidance and preferences for facial symmetry and sexual dimorphism: A registered report

Over the past decade, a small literature has tested how trait-level pathogen-avoidance motives (e.g., disgust sensitivity) and exposure to pathogen cues relate to preferences for facial symmetry and sexual dimorphism. Results have largely been interpreted as suggesting that the behavioral immune system influences preferences for these features in potential mates. However, findings are limited by small sample sizes among studies reporting supportive evidence, the use of small stimulus sets to assess preferences for symmetry and dimorphism, and design features that render implications for theory ambiguous (namely, largely only investigating women's preferences for male faces). Using a sample of 954 White young adult UK participants and a pool of 100 White young adult stimuli, the current registered report applied a standard two-alternative forced-choice approach to evaluate both men's and women's preferences for both facial symmetry and dimorphism in both same- and opposite-sex targets. Participants were randomly assigned to either a pathogen prime or a control prime, and they completed instruments assessing individual differences in pathogen avoidance (disgust sensitivity and contamination sensitivity). Results revealed overall preferences for both facial symmetry and dimorphism. However, they did not reveal a relation between these preferences and disgust sensitivity or contamination sensitivity, nor did they reveal differences in these preferences across control and pathogen prime conditions. Null results of pathogen-avoidance variables were consistent across participant sex, target sex, and interactions between participant sex and target sex. Overall, findings cast doubt on the hypothesis that pathogen-avoidance motives influence preferences for facial symmetry or dimorphism.     

Is obesity un-American? Disease concerns bias implicit perceptions of national identity

The current research examined whether Americans incorporate obesity into their national identity, and further investigated the role an evolved behavioral immune system plays in shaping Americans' perceptions of obesity and national identity. Two studies revealed that obesity is not, on the whole, incorporated into the American identity at an implicit level. Moreover, when disease concerns were salient, either because of an experimental priming manipulation (Study 1) or due to recent illness (Study 2), thin individuals (for whom obesity may represent a particularly atypical morphology and thus a heuristic cue to disease) implicitly excluded obesity from the American identity to a greater degree. Thus, implicitly categorizing a subgroup of people as an outgroup pathogen threat may promote behavioral avoidance, exclusion, or stigmatization. This behavioral avoidance, could, in turn lead to less risk of fitness-reducing disease contraction. Further implications for evolutionary theories of disease avoidance, group identity, and discrimination are discussed.     

Disgust versus Lust: Exploring the Interactions of Disgust and Fear with Sexual Arousal in Women

Sexual arousal is a motivational state that moves humans toward situations that inherently pose a risk of disease transmission. Disgust is an emotion that adaptively moves humans away from such situations. Incongruent is the fact that sexual activity is elementary to human fitness yet involves strong disgust elicitors. Using an experimental paradigm, we investigated how these two states interact. Women (final N=76) were assigned to one of four conditions: rate disgust stimuli then watch a pornographic clip; watch a pornographic clip then rate disgust stimuli; rate fear stimuli then watch a pornographic clip; or watch a pornographic clip then rate fear stimuli. Women’s genital sexual arousal was measured with vaginal photoplethysmography and their disgust and fear reactions were measured via self-report. We did not find that baseline disgust propensity predicted sexual arousal in women who were exposed to neutral stimuli before erotic content. In the Erotic-before-Disgust condition we did not find that sexual arousal straightforwardly predicted decreased image disgust ratings. However, we did find some evidence that sexual arousal increased self-reported disgust in women with high trait disgust and sexual arousal decreased self-reported disgust in women with low trait disgust. Women who were exposed to disgusting images before erotic content showed significantly less sexual arousal than women in the control condition or women exposed to fear-inducing images before erotic content. In the Disgust-before-Erotic condition the degree of self-reported disgust was negatively correlated with genital sexual arousal. Hence, in the conflict between the ultimate goals of reproduction and disease avoidance, cues of the presence of pathogens significantly reduce the motivation to engage in mating behaviors that, by their nature, entail a risk of pathogen transmission.     

Disgust sensitivity relates to affective responses to – but not ability to detect – olfactory cues to pathogens

Hundreds of studies have assessed variation in the degree to which people experience disgust toward substances associated with pathogens, but little is known about the mechanistic sources of this variation. The current investigation uses olfactory perception and threshold methods to test whether it is apparent at the cue-detection level, at the cue-interpretation level, or both. It further tests whether relations between disgust sensitivity and olfactory perception are specific to odors associated with pathogens. Two studies (N's = 119 and 160) of individuals sampled from a Dutch university each revealed that pathogen disgust sensitivity relates to valence perceptions of odors found in pathogen sources, but not to valence perceptions of odors not associated with pathogens, nor to intensity perceptions of odors of either type. Study 2, which also assessed olfactory thresholds via a three-alternative forced-choice staircase method, did not reveal a relation between pathogen disgust sensitivity and the ability to detect an odor associated with pathogens, nor an odor not associated with pathogens. In total, results are consistent with the idea that pathogen disgust sensitivity relates to how olfactory pathogen cues are interpreted after detection, but not necessarily to the ability to detect such cues.     

Feelings of Disgust and Disgust-Induced Avoidance Weaken following Induced Sexual Arousal in Women

Background

Sex and disgust are basic, evolutionary relevant functions that are often construed as paradoxical. In general the stimuli involved in sexual encounters are, at least out of context strongly perceived to hold high disgust qualities. Saliva, sweat, semen and body odours are among the strongest disgust elicitors. This results in the intriguing question of how people succeed in having pleasurable sex at all. One possible explanation could be that sexual engagement temporarily reduces the disgust eliciting properties of particular stimuli or that sexual engagement might weaken the hesitation to actually approach these stimuli.

Methodology

Participants were healthy women (n = 90) randomly allocated to one of three groups: the sexual arousal, the non-sexual positive arousal, or the neutral control group. Film clips were used to elicit the relevant mood state. Participants engaged in 16 behavioural tasks, involving sex related (e.g., lubricate the vibrator) and non-sex related (e.g., take a sip of juice with a large insect in the cup) stimuli, to measure the impact of sexual arousal on feelings of disgust and actual avoidance behaviour.

Principal Findings

The sexual arousal group rated the sex related stimuli as less disgusting compared to the other groups. A similar tendency was evident for the non-sex disgusting stimuli. For both the sex and non-sex related behavioural tasks the sexual arousal group showed less avoidance behaviour (i.e., they conducted the highest percentage of tasks compared to the other groups).

Significance

This study has investigated how sexual arousal interplays with disgust and disgust eliciting properties in women, and has demonstrated that this relationship goes beyond subjective report by affecting the actual approach to disgusting stimuli. Hence, this could explain how we still manage to engage in pleasurable sexual activity. Moreover, these findings suggest that low sexual arousal might be a key feature in the maintenance of particular sexual dysfunctions.     

Risk of parasite transmission influences perceived vulnerability to disease and perceived danger of disease-relevant animals

Adaptationist view proposes that emotions were shaped by natural selection and their primary function is to protect humans against predators and/or disease threat. This study examined cross-cultural and inter-personal differences in behavioural immune system measured by disgust, fear and perceived danger in participants from high (Turkey) and low (Slovakia) pathogen prevalence areas. We found that behavioural immune system in Turkish participants was activated more than those of Slovakian participants when exposed to photographs depicting disease-relevant cues, but not when exposed to disease-irrelevant cues. However, participants from Slovakia, where human to human disease transmission is expected to be more prevalent than in Turkey, showed lower aversion in Germ Aversion subscale supporting hypersensitiveness of the behavioural immune system. Having animals at home was less frequent both in Turkey and in participants who perceived higher danger about disease relevant animals. Participants more vulnerable to diseases reported higher incidence of illness last year and considered perceived disease-relevant animals more dangerous than others. Females showed greater fear, disgust and danger about disease-relevant animals than males. Our results further support the finding that cultural and inter-personal differences in human personality are influenced by parasite threat.     

Pathogen disgust,but not moral disgust,changes across the menstrual cycle

The Compensatory Prophylaxis Hypothesis (CPH) proposes that during periods of increased susceptibility to infections, e.g., during the luteal phase of the menstrual cycle when progesterone suppresses immune function, women should feel more disgust toward pathogen cues and behave prophylactically. We investigate differences in disgust sensitivity and contamination sensitivity during different phases of the menstrual cycle in regularly cycling, healthy 93 rural and urban Polish women using the within-subject design. Disgust sensitivity was measured during two different phases of a menstrual cycle: 1) the follicular phase (the 5th or 6th day of the cycle) and 2) the luteal phase (on the 5th day after a positive ovulatory test or on 20th day of a cycle if the result of the ovulatory test was not positive). In the luteal phase, women scored higher on the Pathogen Disgust of the Three-Domain Disgust Scale, the Contamination Obsessions and Washing Compulsions Subscale of Padua Inventory, and on ratings of photographs showing sources of potential infections than in the follicular phase. Moral Disgust of the Three-Domain Disgust Scale did not differ between cycle phases. Hence, results suggest that women feel more disgusted toward cues to pathogens during the luteal phase, when susceptibility to infection is greater. We suggest that it is necessary to incorporate ovulatory testing as well as to conduct repeated measurements of disgust sensitivity in future tests of the CPH. Moreover, we believe that understanding how the feeling of pathogen disgust varies across the menstrual cycle and in relation to progesterone levels could be useful in designing effective infectious diseases prevention strategies for women.     

Social neuroscience of disgust

Disgust can be thought of as an affective system that has evolved to detect signs of pathogens, parasite and toxins as well as to stimulate behaviors that reduce the risk of their acquisition. Disgust incorporates social cognitive mechanisms to regulate exposure to and, or anticipate and avoid exposure to pathogens and toxins. Social cognition entails the acquisition of social information about others (ie, social recognition) and from others (ie, social learning). This involves recognizing and assessing other individuals and the pathogen/parasite/contamination/toxin threat they pose and deciding about when and how to interact with and, or avoid them. Social cognition provides a frame‐work for examining the expression of disgust and the associated neurobiological mechanisms. Here, we briefly consider the relations between social cognition and pathogen/parasite/toxin avoidance behaviors. We briefly discuss aspects of: (1) the odor mediated social recognition of actual and potentially infected individuals and the impact of parasite/pathogen threat on disgust mate and social partner choice; (2) the roles of “out‐groups” (strangers, unfamiliar individuals) and “in‐groups” (familiar individuals) in the expression of disgust and pathogen avoidance behaviors; (3) individual and social learning of disgust and empathy for disgust; (4) toxin elicited disgust and anticipatory disgust; (5) the neurobiological mechanisms, and in particular the roles of the nonapeptide, oxytocin and estrogenic mechanism associated with social cognition and the expression of disgust. These findings on the social neuroscience of disgust have a direct bearing on our understanding of the roles of disgust in shaping human and nonhuman social behavior.     

Disgust sensitivity predicts sociosexuality across cultures

Restricted sociosexuality has been linked to sexual disgust, suggesting that decreasing sexual behavior may be a pathogen avoidance technique. Using the behavioral immune system framework, which posits that humans experience disgust after exposure to pathogen cues, we replicate and expand on previous studies by analyzing the influence of three domains of disgust (sexual, moral, pathogen) on psychological (desire and attitude) and behavioral domains of sociosexuality (SOI) in four diverse samples: American university students (n = 155), Salvadoran community members (n = 98), a global online sample (n = 359), and a four-country online sample (US, India, Italy, and Brazil; n = 822) collected during the SARS-CoV-2 pandemic. In contrast with previous studies, we account for shared variance in sexual, pathogen, and moral disgust by entering all three in a multiple regression to predict composite SOI. In both large samples, sexual disgust and pathogen disgust had opposing effects on composite SOI; that is, higher sexual disgust and lower pathogen disgust were associated with more restricted composite SOI. Additionally, we constructed a multi-group structural equation model (SEM) to determine the impact of each domain of disgust on each domain of SOI across all our samples simultaneously, while controlling for age and sex. Within this model we also assessed how the psychological domains of SOI – attitude and desire – mediate the relationship between disgust and sociosexual behavior. Pathogen disgust positively predicted SOI attitude and desire, but not behavior, consistently across all groups. SOI behavior was only predicted by pathogen disgust when mediated by SOI attitude, again across all groups, suggesting that behavior seems to be driven largely by the psychological facets of SOI. We discuss these findings in light of the behavioral immune system and the bet-hedging hypothesis, which make opposing predictions on the relationship between infection risk and sexual behavior.     

Parasite primes make foreign-accented English sound more distant to people who are disgusted by pathogens (but not by sex or morality)

To avoid disease, people should maintain close ties with ingroup members but maintain distance from outgroup members who possess novel pathogens. Consistent with this disease-avoidance hypothesis, pathogenic stimuli, as well as increased personal vulnerability to disease, are associated with xenophobic and ethnocentric attitudes. Researchers assume that this disease-avoidance process is an automatic emotional response that compels negative attitudes and behavioral avoidance. However, when outgroup contact can represent fitness costs or benefits, and when group membership is an uncertain cue to infection risk, it becomes a fitness advantage for a social perceiver to track group membership and thus infection risk. Given that accents can be a cue to group membership, we predicted that the perception of linguistic similarity to ingroup speakers and dissimilarity from outgroup speakers would increase with individual differences in pathogen disgust, and that this association would be most apparent when threat of disease was salient. This hypothesis was confirmed in two experiments. Further, the mechanism was domain specific—disgust due to sexual acts and moral violations did not moderate perceived linguistic distance. The disease-avoidance mechanism is not just an automatic disgust-based reaction; it also operates through the cognitive appraisal of social distance.